Neuronal background of positioning of the posterior tentacles in the snail Helix pomatia

The location of cerebral neurons innervating the three recently described flexor muscles involved in the orientation of the posterior tentacles as well as their innervation patterns were investigated, applying parallel retrograde Co- and Ni-lysine as well as anterograde neurobiotin tracings via the olfactory and the peritentacular nerves. The neurons are clustered in eight groups in the cerebral ganglion and they send a common innervation pathway via the olfactory nerve to the flexor and the tegumental muscles as well as the tentacular retractor muscle and distinct pathways via the internal and the external peritentacular nerves to these muscles except the retractor muscle. The three anchoring points of the three flexor muscles at the base of the tentacle outline the directions of three force vectors generated by the contraction of the muscles along which they can pull or move the protracted tentacle which enable the protracted tentacle to bend around a basal pivot. In the light of earlier physiological and the present anatomical findings we suggest that the common innervation pathway to the muscles is required to the tentacle withdrawal mechanism whereas the distinct pathways serve first of all the bending of the protracted posterior tentacles during foraging

Observation of Dirac plasmons in a topological insulator

Plasmons are the quantized collective oscillations of electrons in metals and doped semiconductors. The plasmons of ordinary, massive electrons are since a long time basic ingredients of research in plasmonics and in optical metamaterials. Plasmons of massless Dirac electrons were instead recently observed in a purely two-dimensional electron system (2DEG)like graphene, and their properties are promising for new tunable plasmonic metamaterials in the terahertz and the mid-infrared frequency range. Dirac quasi-particles are known to exist also in the two-dimensional electron gas which forms at the surface of topological insulators due to a strong spin-orbit interaction. Therefore,one may look for their collective excitations by using infrared spectroscopy. Here we first report evidence of plasmonic excitations in a topological insulator (Bi2Se3), that was engineered in thin micro-ribbon arrays of different width W and period 2W to select suitable values of the plasmon wavevector k. Their lineshape was found to be extremely robust vs. temperature between 6 and 300 K, as one may expect for the excitations of topological carriers. Moreover, by changing W and measuring in the terahertz range the plasmonic frequency vP vs. k we could show, without using any fitting parameter, that the dispersion curve is in quantitative agreement with that predicted for Dirac plasmons.Comment: 11 pages, 3 figures, published in Nature Nanotechnology (2013

Mid-infrared plasmons in scaled graphene nanostructures

Plasmonics takes advantage of the collective response of electrons to electromagnetic waves, enabling dramatic scaling of optical devices beyond the diffraction limit. Here, we demonstrate the mid-infrared (4 to 15 microns) plasmons in deeply scaled graphene nanostructures down to 50 nm, more than 100 times smaller than the on-resonance light wavelength in free space. We reveal, for the first time, the crucial damping channels of graphene plasmons via its intrinsic optical phonons and scattering from the edges. A plasmon lifetime of 20 femto-seconds and smaller is observed, when damping through the emission of an optical phonon is allowed. Furthermore, the surface polar phonons in SiO2 substrate underneath the graphene nanostructures lead to a significantly modified plasmon dispersion and damping, in contrast to a non-polar diamond-like-carbon (DLC) substrate. Much reduced damping is realized when the plasmon resonance frequencies are close to the polar phonon frequencies. Our study paves the way for applications of graphene in plasmonic waveguides, modulators and detectors in an unprecedentedly broad wavelength range from sub-terahertz to mid-infrared.Comment: submitte

Inverse magnetocaloric effect in ferromagnetic Ni-Mn-Sn alloys

The magnetocaloric effect (MCE) in paramagnetic materials has been widely used for attaining very low temperatures by applying a magnetic field isothermally and removing it adiabatically. The effect can be exploited also for room temperature refrigeration by using recently discovered giant MCE materials. In this letter, we report on an inverse situation in Ni-Mn-Sn alloys, whereby applying a magnetic field adiabatically, rather than removing it, causes the sample to cool. This has been known to occur in some intermetallic compounds, for which a moderate entropy increase can be induced when a field is applied, thus giving rise to an inverse magnetocaloric effect. However, the entropy change found for some ferromagnetic Ni-Mn-Sn alloys is just as large as that reported for giant MCE materials, but with opposite sign. The giant inverse MCE has its origin in a martensitic phase transformation that modifies the magnetic exchange interactions due to the change in the lattice parameters.Comment: 12 pages, 4 figures, to appear in Nature Materials (online published, 15 May 2005

Modulation of enhancer looping and differential gene targeting by Epstein-Barr virus transcription factors directs cellular reprogramming

Epstein-Barr virus (EBV) epigenetically reprogrammes B-lymphocytes to drive immortalization and facilitate viral persistence. Host-cell transcription is perturbed principally through the actions of EBV EBNA 2, 3A, 3B and 3C, with cellular genes deregulated by specific combinations of these EBNAs through unknown mechanisms. Comparing human genome binding by these viral transcription factors, we discovered that 25% of binding sites were shared by EBNA 2 and the EBNA 3s and were located predominantly in enhancers. Moreover, 80% of potential EBNA 3A, 3B or 3C target genes were also targeted by EBNA 2, implicating extensive interplay between EBNA 2 and 3 proteins in cellular reprogramming. Investigating shared enhancer sites neighbouring two new targets (WEE1 and CTBP2) we discovered that EBNA 3 proteins repress transcription by modulating enhancer-promoter loop formation to establish repressive chromatin hubs or prevent assembly of active hubs. Re-ChIP analysis revealed that EBNA 2 and 3 proteins do not bind simultaneously at shared sites but compete for binding thereby modulating enhancer-promoter interactions. At an EBNA 3-only intergenic enhancer site between ADAM28 and ADAMDEC1 EBNA 3C was also able to independently direct epigenetic repression of both genes through enhancer-promoter looping. Significantly, studying shared or unique EBNA 3 binding sites at WEE1, CTBP2, ITGAL (LFA-1 alpha chain), BCL2L11 (Bim) and the ADAMs, we also discovered that different sets of EBNA 3 proteins bind regulatory elements in a gene and cell-type specific manner. Binding profiles correlated with the effects of individual EBNA 3 proteins on the expression of these genes, providing a molecular basis for the targeting of different sets of cellular genes by the EBNA 3s. Our results therefore highlight the influence of the genomic and cellular context in determining the specificity of gene deregulation by EBV and provide a paradigm for host-cell reprogramming through modulation of enhancer-promoter interactions by viral transcription factors

Ibrutinib in the Treatment of Refractory Chronic Lymphocytic Leukemia

Background & Aims. This paper presents the results of the observational study of ibrutinib in patients with chronic lymphocytic leukemia (CLL), conducted in SP Botkin Municipal Clinical Hospital. The main objective was the analysis of complications of ibrutinib and identification of factors, influencing the dosage regimen; the secondary objective was the estimation of the total response to treatment, event-free and overall survival. Materials & Methods. The study included 96 patients with CLL with indications for ibrutinib therapy. The median age was 64,9 years (range 32–91 years), the study population consisted of 69 (72 %) men and 27 (28 %) women. The condition of 25 (26 %) patients according to the ECOG scale was of > 3 points. The disease of stage C were diagnosed in 36 (37 %) patients . Deletion of 17p/TP53 mutations were detected in 29 (33 %) of 87 patients. Seventy patients had refractory CLL. The median of the number of the lines of the previous therapy was 3 (range 1–9). Adverse events were assessed in accordance with the CTCAE criteria, version 4.0; the bleeding severity was evaluated using ITP-specific bleeding score; hematological complications were classified according to the recommendations of IWCLL-2008. Results. Ibrutinib was administered at a dosage of 420 mg per day daily until progression or intolerable toxicity. The median duration of ibrutinib therapy was 10.3 months. Ibrutinib was shown to have moderate toxicity, mostly of grade I or II. The bleeding was the most frequent complication. Of the hematological complications, thrombocytopenia was the most common (35 %); neutropenia grade III) developed in 26 % of patients. The treatment response was assessed in 92 patients. The overall response to treatment was 89 %. Complete remission, partial remission and partial remission with lymphocytosis were achieved in 4 (4 %), 57 (62 %), and 21 (23 %) patients, respectively. The event-free survival and overall survival by the month 10 was 90 % and 91 %, respectively. For this observation period, ECOG status and the number of the lines of therapy prior to ibrutinib had the prognostic value. Conclusion. Ibrutinib was shown to have high efficiency in relapsed/refractory forms of CLL. The nature of the ibrutinib toxicity is fundamentally different from that of the conventional chemotherapy. The frequency of ibrutinib therapy complications and patients’ non-compliance depends on the intensity of the previous treatment of CLL. Despite a short observation period, it can be concluded that ibrutinib had the greatest impact on the patient’s quality of life when administered for the first relapse. The low toxicity of ibrutinib is likely to allow the combination with other antitumor agents

Azimuthal anisotropy and correlations at large transverse momenta in p+pp+p and Au+Au collisions at sNN\sqrt{s_{_{NN}}}= 200 GeV

Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au+Au collisions at $\sqrt{s_{_{NN}}}$= 200 GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au+Au collisions to those in $p+p$ at the same energy. Elliptic anisotropy, $v_2$, is found to reach its maximum at $p_t \sim 3$ GeV/c, then decrease slowly and remain significant up to $p_t\approx 7$ -- 10 GeV/c. Stronger suppression is found in the back-to-back high-$p_t$ particle correlations for particles emitted out-of-plane compared to those emitted in-plane. The centrality dependence of $v_2$ at intermediate $p_t$ is compared to simple models based on jet quenching.Comment: 4 figures. Published version as PRL 93, 252301 (2004

Azimuthal anisotropy in Au+Au collisions at sqrtsNN = 200 GeV

The results from the STAR Collaboration on directed flow (v_1), elliptic flow (v_2), and the fourth harmonic (v_4) in the anisotropic azimuthal distribution of particles from Au+Au collisions at sqrtsNN = 200 GeV are summarized and compared with results from other experiments and theoretical models. Results for identified particles are presented and fit with a Blast Wave model. Different anisotropic flow analysis methods are compared and nonflow effects are extracted from the data. For v_2, scaling with the number of constituent quarks and parton coalescence is discussed. For v_4, scaling with v_2^2 and quark coalescence is discussed.Comment: 26 pages. As accepted by Phys. Rev. C. Text rearranged, figures modified, but data the same. However, in Fig. 35 the hydro calculations are corrected in this version. The data tables are available at http://www.star.bnl.gov/central/publications/ by searching for "flow" and then this pape

Bethe-hole polarization analyser for the magnetic vector of light

The nature of light as an electromagnetic wave with transverse components has been confirmed using optical polarizers, which are sensitive to the orientation of the electric field. Recent advances in nanoscale optical technologies demand their magnetic counterpart, which can sense the orientation of the optical magnetic field. Here we report that subwavelength metallic apertures on infinite plane predominantly sense the magnetic field of light, establishing the orientation of the magnetic component of light as a separate entity from its electric counterpart. A subwavelength aperture combined with a tapered optical fibre probe can also serve as a nanoscale polarization analyser for the optical magnetic field, analogous to a nanoparticle sensing the local electric polarization. As proof of its functionality, we demonstrate the measurement of a magnetic field orientation that is parallel to the electric field, as well as a circularly polarized magnetic field in the presence of a linearly polarized electric field